Connection to a corrugated pipe or conduit can be made by means of a coupling in which the end of the pipe is inserted, the coupling having a retaining member in the form of a resilient tooth that engages between corrugations to prevent the pipe and coupling being pulled apart after assembly. The coupling may have a tapering bore forming a close fit with the outside of the pipe so as to seal the pipe with the coupling. Couplings of this kind are described, for example, in U.S. Pat. Nos. 5,094,482, 5,041,256, GB2225550, U.S. Pat. Nos. 5,150,930 and 4,923,227 and are sold by Adaptaflex Limited of Coleshill, Birmingham, UK. Although the seal provided by these couplings is satisfactory in many situations, there are some applications where a more effective seal is needed.